My HVAC plenum is a near square metal box. I presume insulated on the inside.
It is connected of course to the Coil Box on one side.
The top has no ducts exiting. Nor does the bottom which is just a few inches over the drip pan which rests on the ceiling joists.
All the round grey vinyl covered ducts exit on the remaining 3 sides.
I am not happy with the low output in certain rooms.
I also hate the spaghetti bowl mess of ducts running everywhere and the task of climbing over and working around so many of them.
Would it have been wrong for the plenum to have a few ducts exit on top?
Would it be unwise to raise (in the next replacement the whole furnace (horizontal in attic) and likewise the input box and the new plenum and use the bottom of the new plenum for duct exit as well?
BTW are plenums made on the job site usually?
I mean do you guys cut the holes in blank plenum panels?
How do you do this if so?
Seems to me that the ideal plenum would be a large globe.
Or does it matter that there are "dead corners" inside the plenum?
any ideas appreciated.